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<pre class="textdiagram" id="fig48">
     Cluster 1          :          Cluster 2
                        :
                        :
+---+  +---+  +---+     :     +---+  +---+  +---+
| C |  | C |  | C |     :     | C |  | C |  | C |
+-+-+  +-+-+  +-+-+     :     +-+-+  +-+-+  +-+-+
  |      |      |       :       |      |      |
  |      |      |       :       |      |      |
+-+------+------+-+     :     +-+------+------+-+
|     Broker      |<--------->|     Broker      |
+-+------+------+-+     :     +-+------+------+-+
  |      |      |       :       |      |      |
  |      |      |       :       |      |      |
+-+-+  +-+-+  +-+-+     :     +-+-+  +-+-+  +-+-+
| W |  | W |  | W |     :     | W |  | W |  | W |
+---+  +---+  +---+     :     +---+  +---+  +---+
                        :
</pre>
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